In recent years, disk devices such as magnetic disk drives and optical disk drives have been widely used as image recording devices or external recording devices of computers.
As such the disk device, for example, a magnetic disk drive generally comprises a magnetic disk, a spindle motor which supports and rotates the magnetic disk, a head stack assembly supporting magnetic heads, a circuit board unit, etc, which are provided in a housing. The head stack assembly comprises a bearing portion and a plurality of head gimbal assemblies extending from the bearing portion. The head gimbal assemblies each comprise a suspension supporting the magnetic head and a wiring trace electrically connecting the magnetic head to the circuit board unit.
The circuit board unit comprises a base portion on which a connector, etc. are mounted, and a main flexible printed circuit board (hereinafter main FPC) extending from the base portion to the vicinity of the bearing portion. The main FPC includes an extended end portion having a plurality of connection portions, at which a plurality of connection pads are provided, respectively. The connection portions are attached to the bearing portion of a head actuator.
A manufacturing process of such the magnetic disk drive as stated above includes steps of heating the entire magnetic disk drive, and adjusting the operation of the disk drive and inspecting the disk drive in thermal resistance, at various temperatures. In this case, there is a possibility that gas will generate from components in the housing, such as a bearing, rubber and a flexible printed circuit board, and contaminate the inside of the housing. Also, even if the magnetic disk drive is assembled in a clean room, it can be considered that generated gas collects in the housing, and adversely affects the recording medium or the magnetic heads. Consequently, the reliability of the disk device is lowered.